PHP 生成GUID（UUID）

 
/**
     * 生成GUID（UUID）
     * @access public
     * @return string
     * @author knight
     */
    function createGuid()
    {
        if (function_exists('com_create_guid')){
            return com_create_guid();
        }else{
            mt_srand((double)microtime()*10000);
            $charid = strtoupper(md5(uniqid(rand(), true)));
            $hyphen = chr(45);// "-"
            $uuid = chr(123)// "{"
                .substr($charid, 0, 8).$hyphen
                .substr($charid, 8, 4).$hyphen
                .substr($charid,12, 4).$hyphen
                .substr($charid,16, 4).$hyphen
                .substr($charid,20,12)
                .chr(125);// "}"
            return $uuid;
        }
    }